Durable germicidal finish for hydrophobic polyamide textile materials



United States Patent 3,140,227 DURABLE GERMICIDAL FINISH FOR HYDRO-PHOBIC POLYAMIDE TEXTILE MATERIALS Philip B. Roth, Somerville, andLeonard B. Hallows, New Brunswick, N.J., assignors to American CyanamidCompany, New York, N.Y., a corporation of Maine No Drawing. Filed Feb.14, 1961, Ser. No. 89,104 9 Claims. (Cl. 167-38.6)

This invention relates to a durable anti-bacterial finish for synthetichydrophobic polyamide textile materials, to a method of improving thedurability of the antibacterial finish when applied to such textilematerials, and to the materials thus treated.

In recent years, increased attention has been given to the developmentof textile finishes which have become known as purifying finishes. Thesefinishes are antibacterial and as such are intended to reduce the numberof microorganisms residing in the materials, whereby such materials maybe used with less danger from harmful bacteria. These purifyingfinishes, when applied to articles of clothing worn close to the body,are also helpful in the prevention of development of odor.

Satisfactory purifying finishes should be durable preferably to bothlaundering and dry cleaning and active at low concentrations against abroad spectrum of microorganisms. It should be non-toxic andnon-allergenic. It should not have the tendency to sensitize the wearerof the textile material to the material to be finished. It should nothave the quality of allowing strains of bacteria to develop which areresistant to the antibacterial agent of the finish. Still further, itshould be resistant to home and commercial laundering conditions andshould impart only acceptable modifications of the hand to the textilematerials.

At present there are many chemical compounds being used as antibacterialfinishes for textile materials. In most instances the methods ofapplying these have become conventional. A majority of these finishesare known to those skilled in the art of textile finishing asnon-durable and thus are readily removed from the treated materials bylaundering or dry cleaning. Few, if any, are classified as durablefinishes specifically on synthetic hydrophobic polyamide textilematerials.

Thus, there is a great need for a good, durable antibacterial finish fortextile materials of the hydrophobic type and in particular thehydrophobic polyamide type, such as nylon. Neomycin salts are known tobe very effective antibacterial compounds and applications of these totextile materials from aqueous solutions of low concentrations have beeneffective in destroying bacteria and in eliminating odor caused byperspiration. However, on synthetic hydrophobic polyamide fibers such asnylon, while excellent zones. of inhibition to Staph. aureus, have beenobtained initially, these zones are reduced drastically by ordinarywashing or laundering operations.

With regard to the use of neomycin salts as purifying finishes, such useis described in US. Patent No. 2,830,- 011, the subject matter of whichis incorporated herein by reference.

Accordingly, it is an object of the present invention to provide aprocess for improving the durability of neomycin salts to synthetichydrophobic polyamide textile materials and to provide such textilematerials having an improved durable antibacterial finish.

These and other objects of the present invention will become moreapparent from the detailed description thereof set forth hereinbelow.

According to the present invention, a method for providing a durableantibacterial finish on synthetic hydrophobic polyamide textilematerials is contemplated, which method comprises treating suchmaterials with neomycin $340,227 Patented July 7, 1964 and a polyacrylicacid and thereafter drying the material.

The term neomycin is used herein in its ordinary sense to denote thecommercially available product which is called neomycin, it actuallybeing a mixture of two very closely related antibiotics known morespecifically as neomycin B and neomycin C. The term is also intended tocover neomycin as just defined, the individual components of the complexor its salts, of which the sulfate is most generally available. Othersalts of neomycin have been used in finishing textiles of the typecontemplated herein with good results. Among these may be mentionedneomycin-parahydroxy benzoate, neomycin sulfanilate, neomycinN-tartrate, neomycin propionate and the like.

By a polyacrylic acid, as that term is employed herein, it is intendedto include polyacrylic acid per se, polymethacrylic acid, polyethacrylicacid, and the like, polyacrylic acid per se being preferred. Thesepolyacrylic acids should be characterized by a molecular weight of fromabout 2,500 up to about 250,000, although higher molecular weights up tothe limit of water solubility are fully contemplated. Preferably themolecular weight is from about 2,500 up to 200,000, while ideally themolecular weight appears to be between about 5,000 and about 20,000. Themolecular weight values referred to may be determined by the lightscattering technique such as described in Florys Principles of PolymerChemistry, Cornell University Press (1953), at pages 283-303, inclusive.These polyacrylic acids have pHs of less than 4 and usually a value ofbetween 1 and 3.

By synthetic hydrophobic polyamide textile materials it is meant formedfabrics, whether they be woven, knitted, felted or otherwise formed,containing at least about 30% of nylon and preferably at least 50% ofnylon. The balance, if any, may be cellulosic, such as cotton, rayon,linen and the like. In addition, it may be comprised of polyesterfibers, acrylic fibers, silk and wool fibers. It will be evident thatthe balance may be any of the above or other known fibers employed aloneor in combination with one another.

By nylon it is meant any of the hydrophobic polyamides which aregenerally and conventionally referred to by this term and which normallyare the result of a reaction between a diamine and a dibasic acid,although sometimes prepared by the polymerization of an omegaamino acid.Such nylons include nylons 66, 48, 200', 610, 6, 11 and the like.

The neomycin may be employed within the range of from between 0.001 to 1inclusive and preferably is employed in amounts of from between about0.01 to 0.05% based on the dry weight of the synthetic polyamide textilematerial.

The polyacrylic acids may be employed within the range of from betweenabout 0.5 and 5%, though preferably are employed in amounts of frombetween 0.5 and 3%, again based on the dry weight of the synthetichydrophobic polyamide textile material.

We have found it advantageous in some instances to employ a curingaccelerator or a catalyst for the polyacrylic acid. Suitable catalystsare those metal salts which are strongly acidic and in particular themetal salts of zinc and aluminum. Illustrative of such accelerators arezinc chloride, zinc nitrate, aluminum chloride, aluminurn nitrate andthe like, Such accelerators are usually employed in amounts of frombetween about 3 and 10% and preferably in amounts of from between 5 and7%, based on the weight of the polyacrylic acid. It should be notedagain that the use of such catalysts is optional although theiremployment in some instances has resulted in improved durability of theantibacterial finish to which this invention is directed.

After application of the neomycin and the polyacrylic acid to thesynthetic hydrophobic polyamide textile material, the material isnormally dried and the material heated to curing temperatures. Normallyfor drying of the material temperatures within the range of from between200 and about 300 and preferably temperatures of from between about 215to about 230 F. are employed. Curing of the finished polyamide textilematerials is normally effected within the range of between 225 to 375 F.though preferably within the range of 275 to 325 F.

In the application of the neomycin and the polyacrylic acid, it ispreferred that the polyacrylic acid be applied first to the textilematerial, drying and curing the material and thereafter applying theneomycin solution. Normally thereafter the material is dried. Thesubsequent heat treatment may include the employment of temperatureswithin the curing range set forth hereinabove. Alternatively, theneomycin and the polyacrylic acid may be applied simultaneously from asingle treating bath or solution. The application of the neomycin firstfollowed by the application of the polyacrylic acid is less desirablethan either the above alternatives in View of the fact that thedurability of the finish, which is believed to be based on the abilityof the polyacrylic acid to associate itself with the textile materialfibers, must then be effected through a layer or coating of neomycin.While such procedures do to some extent improve the durability of thefinish, it is decidedly less desirable than the preferred alternativesset forth hereinabove.

In order that the present invention may be more fully understood, thefollowing examples are given primarily by way of illustration. Nospecific details or enumerations contained therein should be construedas limitations on the present invention except insofar as they appear inthe appended claims. All parts and percentages are by weight unlessotherwise specifically designated.

In the examples hereinafter, references will be made to variousprocedures, methods and tests. In order to facilitate a more thoroughunderstanding of these examples, the following glossary is set forth.

PREPARATION OF TREATING MATERIALS (1) One Bath Method The polyacrylicacid used is diluted in approximately one half of the required water atroom temperature. T this is added the required amount of dilute neomycinsulfate plus additional water to the required total weight. In instanceswhere an accelerator is used, it is entered into the dilution prior tothe final addition of water.

Where neomycin is used alone it is diluted with room temperature waterto the proper concentration and total weight.

(2) Two Bath Method (a) The polyacrylic acid used is diluted in roomtemperature water to the required concentration and total weight.

(b) The neomycin sulfate is diluted with room temperature water to therequired concentration and total weight.

The polyacrylic acid (a) is applied to the textile material and thetreated material is dried for 1 minute at 225 F. and cured. The materialis then subjected to the neomycin sulfate treatment (b) followed byeither drying or curing at desired temperatures.

METHOD OF APPLICATION The experiments described in this application wereperformed by applying the treating compositions to the textile materialsby means of a conventional three roll padder.

DRYING OR CURING METHODS Drying or curing the treated materials wasaccomplished on a pin tenter frame passing through a heating chamber atthe desired temperature.

r None WASHING A METHOD AGAR DIFFUSION TEST METHOD Bacterial inhibitiontests are made on treated fabric by the following method. Discs (11.5mm.) of the treated fabrics are placed on an agar plate inoculated withbacterial culture. After several hours of contact, the discs are removedand the plate incubated overnight. The activity of the compound used onthe fabric discs is recorded as the diameter (in mm.) of the clear areaat the site of the discs. An effective agent will show a clear area witha diameter greater than that of the disc itself (11.5 mm.).

The larger the clear area, the greater is the compounds activity. Theactivity under the fabric disc is also noted where there is no zoneoutside the area covered by the fabric. The area under the disc of thefabric is rated as follows:

CCompletely clear area underneath disc. P--At least 75 clear areaunderneath disc. S-VS--Less than 75% clear area underneath disc. NNone.

Example 1 Applications of 1.0% or 5.0% solids (owf.) polyacrylic acid(5,00010,000 mol. wt.) plus 6% solids zinc chloride (based on acrylicacid) were made from aqueous solutions on nylon taffeta by normalpadding methods.

The swatches were dried for 1 minute at 225 F. followed by curing at 300F. for 9 minutes. The thus treated fabrics were then padded with aqueoussolutions of neomycin sulfate whereby 0.05% solids neomycin sulfate wasdeposited on the textile materials, followed by drying at 225 F. for 1minute. A control swatch of nylon treated with 0.05% solids neomycinsulfate alone was also processed. Antibacterial tests were performed bythe aforementioned test method. Test results are shown in Table I.

The antibacterial activity after washing is much improved by the use ofpolyacrylic acid as a pretreatment for neomycin sulfate in comparison toneomycin sulfate treatment alone.

TION TO Staph. aureus (DIA. MM

Treatment? Pgcent Solids Initially 1 Wash 1 3Washes 9Washes VS O 0.05%Neomycin Sulfate 1.0% Polyacrylie acid topped with 0.05% N eomyeinSulfate 5.0% Polyacrylic acid topped with 0.05% N eomycin Sulfate.

1 Automatic washer at F. using neutral soap.

Example 2 Applications of 0.3, 0.6, 0.9 or 1.2% solids (owf.)polyacrylic acid (mol. wt. 5,00010,000) plus 6.0% zinc chloride (basedon acrylic acid solids) were made on filament nylon taffeta by paddingfollowed by drying at 225 F. for 1 minute and a subsequent cure at 310for 9 minutes. The treated swatches were aftertreated with neomycinsulfate solutions depositing 0.045% solids (owf.) on the fabric followedby drying at 225 F. for 1 minute. A control swatch of nylon materialtreated with 0.045% solids (owf.) neomycin sulfate only and TABLEII.-BAOTERICIDAL ACTIVITY-ZONES 0F INHIBI- TION TO Staph. aureus (DIA.MM.)

Treatment, Percent Solids Initially After 1 After 4 After 9 (owf.) Wash1 Washes l Washes 1 None N N-C VS S 0.045% Neomycin Sulfate. 21. 6 14. 412. 0 12. 0 0.3% Polyacrylic acid 2 topped with 0.045% Neomycin Sulfate21. 2 20. 7 17. 7 15. 7 0.6% Polyacrylic acid 2 topped with 0.045% Neomycin Sulfate 21.0 21. 1 17.9 15. 3 0.9% Polyacrylic acid 3 toppedwith 0.045% Neomycin Sulfate 20. 7 20. 7 18. 8 17. 0 1.2% Polyacrylicacid 2 topped with 0.045% N eomycin Sulfate 21. 4 21.2 20. 0 17. 4

1 Automatic washes at 140 F. using neutral soap. 2 6% zinc chloride usedbased on acrylic acid solids.

Example 3 TABLE IIIEBAOTERICIDAL ACTIVITYZONES OF IN- IBITION TO Staph.aureas (DIA. MM.)

Treatmentsk Pefigcent Solids Initially 1 Wash 1 4Washcs QWashes None NN-C VS S 0.045% Neomycin Sulfate" 21.6 14. 4 12.0 12. 0 0.045% NeomyconSulfate plus 1.2% Polyacrylic acid. 15.1 13. 4 13. 7 13. 6 0.045%Neomycin Sulfate plus 0.9% Polyacrylic acid. 16. 6 15.2 16.2 15.0 0.045%Neomycin Sulfate plus 0.6% Polyacrylic acid. 16. 9 17. 3 16.3 13.1

1 Automatic washes at 140 F. using neutral soap. 6% zinc chloride usedwith polyacrylic acid based on acid wt.

Example 4 Applications of 0.05% solids (owf.) neomycin sulfate alone, incombination with 0.75% solids (owf.) polyacrylic acid (mol. wt.5,00010,000) or 0.75 solids (owf.) polyacrylic acid (mol. wt.5,000-10,000) plus zinc chloride as catalyst were made on filament nylontaffeta. All of the treated fabrics were dried for 1 minute at 225 F.Portions of the materials treated with the combined compounds Weresubjected to further heating at 290 F. for 6 minutes. Test results afterwash cycles are shown in Table IV.

The results show that the use of polyacrylic acid with neomycin sulfateimproves the zones of inhibition against Staph. aureus over thoseimparted by neomycin sulfate alone, after cycles of washings. Theresults also show that it is not essential to use a catalyst with thepolyacrylic acid nor is it necessary to cure the finishes after drying.

TABLE IV.BAOTERIOIDAL ACTIVITY OF ZONES 0F INHIBITION T0 Staph. aureus(DIA. MM.)

. Cure Conditions Treatments on Fabrics,

Percent Solids (owt) Initially 8 Washes Time Temp.

0.05% Neomycin Sulfate None 22. 1 12.0 0.05% Neomycin Sulfate plus 6None 19.8 14. 3 0.75% Polyacrylic acid. 290 19.1 15. 0 g$ i l g if 6None 20 1 15 7 0 oyacry caci an catalyst. 1 290 19. 2 15. 4 None... NV-S 1 6.0% zinc chloride on solids of acrylic acid-all treatments dried1 min. at 225 F.

Example 5 Applications of neomycin sulfate at 0.05% solids (owf.) aloneor in combination with 0.75% or 1.5% solids (owf.) of four differentmolecular weight polyacrylic acids from 5,000 to 100,000 were made onfilament nylon taffeta by padding, followed by drying at 225 F. for 1minute. A portion of each treated nylon sample was cured at 300 F. for 6minutes.

The results of these tests show better initial zones of inhibition wereobtained with the neomycin treatments alone. However, those whereinpolyacrylic acid is used show greater durability to washing. Noappreciable differences were observed in the treatments using diflierentmolecular weight polyacrylic acids. Slight reduction in zones wereobserved on the cured samples when compared with their respective driedcounterparts.

It will be noted in Tables I through 1V hereinabove that in someinstances bactericidal activity seems to be imparted to textilematerials which have not been treated or finished with either neomycinor neomycin and polyacrylic acid. This is believed to be the result ofthe non-treated samples being laundered with the treated samples and tothe migration from the treated to the untreated samples of neomycin inthe wash cycle. It will be noticed that in all instances such activityappears to be slight.

While the above invention has been described essentially in connectionwith neomycin and polyacrylic acids, the finished materials may befurther treated or finished with other textile agents or auxiliaries toachieve particular effects. Thus, known textile finishing resins may beapplied as well as softeners, lubricants and the like.

We claim:

1. A method for providing a durable antibacterial finish on a synthetichydrophobic polyamide textile material which comprises treating thematerial with neomycin and a polyacrylic acid and thereafter drying thetreated material.

2. A method according to claim 1 in which the textile material is nylon.

3. A method according to claim 1 in which the polyacrylic acid has amolecular weight of about 5,000 to 20,000.

4. A method for providing a durable antibacterial finish on a synthetichydrophobic polyamide textile material which comprises applying to saidmaterial neomycin and a water soluble polyacrylic acid so as to applyfrom between about .001 to about 1% of neomycin and from between about.5 and about 5% of polyacrylic acid and thereafter drying the treatedmaterial.

5. A method for providing a durable antibacterial finish on a synthetichydrophobic polyamide textile material which comprises applying to saidmaterial between about .01 and .05 of neomycin and from between about .5and about 2% of polyacrylic acid based on the dry weight of the textilematerial, and from about 5 to about 7% of a strongly acidic catalystbased on the weight of acrylic acid and thereafter subjecting thematerial to elevated temperatures to cure the finish on the material.

6. A process according to claim 5 in which the neomycin and polyacrylicacid are applied simultaneously from the same solution.

7. A process according to claim 5 in which the polyacrylic acid isapplied first and the material dried, and then the neomycin applied.

8. A synthetic hydrophobic polyarnide textile material characterized byan antibacterial finish durable to laundering comprising the reactionproduct of a neomycin salt and polyacrylic acid.

References Cited in the file of this patent UNITED STATES PATENTS2,758,049 Dienna Aug. 7, 1956 2,809,149 Cusumano Oct. 8, 1957 2,826,528Shelanski Mar. 11, 1958 2,830,011 Parker Apr. 8, 1958 2,984,639Stamberger May 16, 1961

5. A METHOD FOR PROVIDING A DURABLE ANTIBACTERIAL FINISH ON A SYNTHETICHYDROPHOBIC POLYAMIDE TEXTILE MATERIAL WHICH COMPRISES APPLYING TO SAIDMATERIAL BETWEEN ABOUT .01 AND .05% OF NEOMYCIN AND FROM BETWEEN ABOUT 5AND ABOUT 2% OF POLYACRYLIC ACID BASED ON THE DRY WEIGHT OF THE TEXTILEMATERIAL, AND FROM ABOUT 5 TO ABOUT 7% OF A STRONGLY ACIDIC CATALYSTBASED ON THE WEIGHT OF ACRYLIC ACID AND THEREAFTER SUBJECTING THEMATERIAL TO ELEVATED TEMPERATURES TO CURE THE FINISH ON THE MATERIAL.